Blasting cap



May 23, 1933,. K. wAssN 4 1,910,487.

BLASTING cAP Filed April '7, 1951r Patented May 23, 1933 PATENT GFFICE KURT WAssN, or

KINGSTON, NEW YORK, ASSIGNOR T0 HERCULES POWDER COMPANY,

OAF WILMINGTON, DELAWARE, A. CORPORATION 0F DELAWARE BLASTING CAP Application led April 7,

My invention relates to improvement in blasting caps, more particularly to a blasting cap adapted to be ired by electrlcity and which is so arranged as to be effectively prevented from accidental iiring.

As is Well known, blasting caps adapted for initiating the detonation of, for example, dynamite, are loaded with, for example, high explosive and are extremely dangerous. Blasting caps of the type adapted to be fired by electricity are provided with lead Wires extending from the explosive container or cap itself for connection with a tiring circuit. The lead wires are usually of substantial length in order that a number of caps may be conveniently connected into a single tiring circuit. The lead Wires are insulated throughout amajor portion of their length, but their free end portions are left uninsulated to enable thefconnection to be made.

While when in storage the lead Wires of blasting caps are coiled up, it is common practice when caps are to 'be used to uncoil the leads and carry the caps to the point of use with the leads dragging on the ground.

-Since there are often stray currents in the ground or the leads may be dragged over a charged rail, or the like, the caps are liable to be fired through the contact of the uninsulated end portions of the lead wires With a charged railv or by a stray current in the ground with resultant serious consequences to one carrying the caps. Heretofore, varous means have been provided whereby the uninsulated end portions of the lead wires are short-circuited with a view to insuring against firing of the cap in the event that the end portions of the lead wires come into contact with a source of current. However, such caps as heretofore provided have not been entirely satisfactory, since the means for short-circuiting the leadsy have involved diiculty in manufacture or in removal in preparingthe cap for use, or causes, as in the case of merely twisting the end portions of the lead wires, such distortion oi: the end portions as to render them inconvenient for making connection with a liring circuit.

Now, in accordance with my invention, I have provided a cap in which the uninsu- 1931. serial No. 528,287.

lated ends of the lead wires are short-circuited so that even though they come in contact with a chargedrail or other source of current, firing of the cap will be prevented. At the same time in the cap in accordance with my inventionvthe means for short-circuiting the lead wires may be easily removed and when removed will leave the free end portions straight and without kinks and in a desirable condition for making connection with a firing circuit.

Having indicated in a general way nature and purpose of my invention,

the will Aproceed to a detailed description of a preferred embodiment thereof with reference to the accompanying drawing in which:

Fig. 1 is a perspective View of a. blasting cagembodying my invention.

ig. 2 is al detail view of the end portions of the lead wires of the cap shown in Fig. 1 with the shunt partially removed.

In the drawing A indicates acontainer formed, for example, of copper and Within which is positioned a suitable explosive charge. From within the container A extend the lead Wires B, B, the inner ends of which are connected by a fusible wire, as a platinum wire, not shown, and the free ends of which are bare or stripped of insulation as shown at c, c. The arrangement of the'explosive charge, lead wires and fusible wire are all in accordance with common practice in elec- D indicates a conductive member, which may be formed, for example, from any metal, as copper, iron, etc., or other material which will conduct an electric current. The mem- -trically fired blasting caps.

ber may be of any desired lshape. in cross section, but will desirably be round, and will desirably be of a length somewhat less than that of the uninsulated lead wires, though it may be of any desired length. The member D is provided with a bend between its ends as shown at e, Figure 1.

As has been indicated, the member D enables the uninsulated ends of the lead wires to be short-circuited for the protection of the cap and for such function the insulated portions of the lead wires are brought tof gether and wrapped or spiraled about the end portions of the member D, as is clearly shown in Figure 1. The lead `Wires, it will be noted, are shortcircuited through contact with the member D and the member will be prevented from slipping out from the Wires due to the bend e.

The uninsulated portions of the lead Wires may be Wrapped around the member D throughout their length, or merely throughout a portion of their length and the membei' D Will desirably extend to the insulated portions of the lead Wires in order to ad'oid maximum protection against accidental liring of the cap.

When it is desired to use the cap embodying my invention, it is only necessary to turn the member D at right angles and pull or Withdraw the Wires from the member as shown in Fig. 2. When the wires are Withdrawn tromthe member D the free ends of the lead Wires will be found to be straight and Without hinlrs, as shown in Fig. 2, so that they may be readily connected with a ring circuit.

llt will now be noted that by virtue oi my invention means are provided whereby blasting caps may be ed'ectively short-circuited and hence protected from accidental detona-` tion, for example, by stray currents or from the uninsulated ends of the leads coming into contact With a charged rail. At the same time the short-circuiting means may be readily removed h'om the leads leaving them straight and Without lcinks so that they may be readily connected into a ring circuit.

What l claim and desire to protect by Letters Patent is:

l. ln a blasting cap, an explosive container, electric leads having uninsulated end portions extending rom said container and a metallic member, the uninsulated endportions oi" the lead Wires as a pair through a length thereof being Wrapped about said meftallic member.

2. ln a blasting cap, an explosive container, electric leads having uninsulated end portions extending from lsaid container and a` relatively rigid metallic member, the uninsulated end portions of the lead Wires as a pair through a length` thereof being Wrapped spirally about said metallic member in contact therewith and With each other.

3. In a blasting cap, an explosive container, electric leads having uninsulated end portions extending from said container and a metallic member, the uninsulated end portions of the lead Wires as a pair through aulength relatively rigi thereof in untwsted relation being wrapped spirally aboutsaid metallic member. p

4f. In a blasting cap, an explosive container,

electric leads having uninsulated end por-` from said container and a metallic vmember, the uninsulated end portions ofthe it wires as a pair through a length thereof from the end et tions extending the insulated portions being Wrapped spirally about said metallic member.

5. In a blasting cap, an explosive container, electric leads having uninsulatedleiid portions extending from said container and a metallic member, the uninsulated end portions of the lead Wires as a pair through a substantial length thereof being wrapped spil-ally about te l i gli tions extending from said container and a me- .p

tallic member having a bend between the ends, the uninsulated end portions of the lead Wires as a pair through a length thereof being Wrapped about said metallic member.

8. ln a blasting cap, an explosive container, electric leads having uninsulated end portions extending from said container and a relatively rigid metallic member substantially circular in cross section and ,of substantial length relative to its cross sectional area, the uninsulated end portions of the lead Wires as a pair through a length thereof being Wrapped about said metallic member.

ln testimony of Which invention, lf have hereunto set my hand, at Kingston,New York., on this 30th day of March, 1931.

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